The present invention relates to an accumulator constituting an air-conditioner or the like using refrigeration oil having very low or no solubility with a refrigerant or having solubility with a characteristic mutually separable from a refrigerant in accordance with temperature conditions.
A general refrigerating cycle is constituted by a compressor 1, a condenser 2, a decompressor 3, an evaporator 4, and an accumulator 5 which are connected circularly by piping as shown in FIG. 6.
For example, in a well-known accumulator 5 disclosed in JP-B-57-17187 and JP-B-62-52230, a suction pipe 11 and a discharge pipe 12 are attached to the intermediate portion and bottom portion of a cylindrical closed vessel 13 respectively, as shown in FIG. 7. One of the openings of the discharge pipe 12 is projected into the cylindrical closed vessel 13 and is provided with an oil recovery hole 10 at a position near a portion where the discharge pipe 12 penetrates the cylindrical closed vessel 13.
Because the conventional accumulator is arranged thus, a mixture of lubricating oil and refrigerant liquid collected in the bottom of the cylindrical closed vessel 13 is sucked into the discharge pipe 12 through the oil recovery hole 10, and sent to the compressor 1.
In addition, in a general refrigerating cycle system, the accumulator is provided before the suction side of the compressor, and required to perform gas-liquid separation of a gas-liquid mixture refrigerant to thereby prevent the compressor from sucking liquid refrigerant, and to return the lubricating oil of the compressor flowing together with the refrigerant to the compressor smoothly without leaving the lubricating oil staying in the accumulator.
In the accumulator 5 shown in FIG. 7 which constitutes such a conventional refrigerating cycle as shown in FIG. 6, a liquid mixture of liquid refrigerant and lubricating oil collected in the bottom of the accumulator has a tendency that a layer rich in the lubricating oil is collected in an upper portion while a layer rich in the liquid refrigerant is collected in a lower portion, particularly at a low temperature, in accordance with the relationship of specific gravities of the both components. Therefore, there has been a fear that only the liquid refrigerant is sucked through the oil recovery hole in accordance with the vertical position of the liquid level of the liquid mixture, and the lubricating oil does not return to the compressor, thereby causing damage in the compressor due to abrasion.
Description has been made above on the assumption that the refrigerant and the lubricating oil are dissolved with each other in the accumulator 5. In the case where the refrigerant is not dissolved in the lubricating oil at all, or has very low solubility in the lubricant oil, the refrigerant and the lubricating oil are separated perfectly in the accumulator 5 so that the lubricating oil is collected in the upper layer side of the liquid refrigerant based on the relationship of specific gravities of the two components, and the lubricating oil does not return to the compressor so long as the lubricating oil comes to the position of the oil recovery hole 10. Accordingly there has been a fear that the lubricating oil stays in the accumulator a, thus causing damage in the compressor.